The invention relates to a disposable injector with a housing in which or on which—in each case at least in some regions—at least one mechanical spring energy reservoir, at least one cylinder/piston unit—which can be filled at least temporarily with active substance, at least one piston—actuating ram and at least one triggering unit are arranged, wherein the spring energy reservoir comprises at least one pretensioned spring element, and wherein at least part of the piston-actuating ram is positioned between the spring energy reservoir and the piston of the cylinder/piston unit.
An injector of this type, inter alia, is known from EP 0 595 508 B1. It has a spring-pretensioned piston, the rear piston rod of which has an elastic region with a throat at its free end. In the region of the throat, the piston is clamped firmly to the injector housing in a frictional and interlocking manner. For this purpose, a triggering pin is inserted in the free end of the piston rod, the triggering pin keeping the throat and the border regions thereof at their maximum diameter. Displacement of the triggering pin enables the diameter of the piston-rod end region to be reduced by the clamping forces in effect, and therefore the clamping effect of the piston rod in relation to the housing is lost. As a result, the spring pretensioned piston moves.
Therefore, the object of the present invention is that of developing a disposable injector of modular design which, with a small overall size, has only a small number of components and, while being easy to handle, ensures safe storage and reliable operation.